For display devices typified by liquid crystal display devices, elements and wirings have been downsized with recent technological innovation and mass production technology has also been improved greatly. Improvement in manufacturing yield is required to achieve lower cost in the future.
If a surge voltage due to static electricity or the like is applied to a display device, an element is broken to produce abnormal display. Thus, manufacturing yield might be decreased. To overcome that, a protection circuit for releasing a surge voltage to another wiring is provided in a display device (see, Patent Documents 1 to 7, for example).